1. Field of the Invention
The present invention relates to a charged particle beam drawing apparatus, and an article manufacturing method using the same.
2. Description of the Related Art
In recent years, as micronization of the element, increasingly complex circuit patterns, or a higher capacity of pattern data advance, the drawing accuracy of drawing apparatuses for use in the manufacturing of devices such as semiconductor integrated circuits need to be improved. As a method for realizing such requirements, a drawing apparatus that draws a pattern on a substrate by controlling the deflection scanning and blanking of a charged particle beam such as an electron beam or the likes is known. In the conventional drawing apparatus, when an exterior magnetic field invades into a charged particle optical system housing, a drawing error may occur due to the positional misalignment of a charged particle beam. Accordingly, Japanese Patent Laid-Open No. 2002-184664 discloses a charged particle beam exposure apparatus that shields an exterior magnetic field by providing a magnetic pole piece (magnetic shielding member: hereinafter referred to as “shielding member”) on a stage on which a substrate is placed. On the other hand, Japanese Patent Laid-Open No. 09-7538 discloses a charged beam drawing apparatus using a plurality of charged particle beams in order to achieve improvements in throughput.
Here, in the exposure apparatus disclosed in Japanese Patent Laid-Open No. 2002-184664, a shielding member placed on a stage always needs to cover the opening of an optical system housing regardless of the position of the stage in association with the movement thereof. Thus, the planar dimension of the shielding member must be greater than the summation of the size of the opening of the optical system housing and the movement stroke of the stage during drawing processing. Also, the drawing apparatus measures the position of the stage with high accuracy using a laser interferometer. The head (detection device) of the interferometer of this type is typically supported from a support member positioning above the stage, via a strut, irradiates a mirror mounted on a side surface of the stage with a laser beam, and receives the laser beam reflected from the mirror. The interferometer head and the strut are disposed at positions so as not to be in contact with the stage which moves in association with drawing.
On the other hand, in the drawing apparatus disclosed in Japanese Patent Laid-Open No. 09-7538, the opening of the optical system housing increases in size due to the use of a plurality of charged particle beams. The planar dimension of the shielding member disclosed in Japanese Patent Laid-Open No. 2002-184664 needs to be greater than the summation of the size of the opening of the optical system housing and the stage stroke. Thus, when the shielding member disclosed in Japanese Patent Laid-Open No. 2002-184664 is applied to the drawing apparatus disclosed in Japanese Patent Laid-Open No. 09-7538, the planar dimension of the shielding member is greater than that of the stage. Here, as disclosed in Japanese Patent Laid-Open No. 2002-184664, when the shielding member is placed below the chuck, the interferometer needs to be placed such that the maximum distance between the interferometer and the mirror is greater than the distance of the stage stroke during drawing processing+(the planar dimension of the shielding member−the planar dimension of the stage)/2. The purpose for this is to avoid a collision between the interferometer or the strut and the shielding member. In other words, when the shielding member disclosed in Japanese Patent Laid-Open No. 2002-184664 is applied to the drawing apparatus disclosed in Japanese Patent Laid-Open No. 09-7538, the interferometer must be arranged spaced at least by the distance of (the planar dimension of the shielding member−the planar dimension of the stage)/2 as compared with the case of no application of the shielding member, resulting in an increase in footprint.